This invention relates to RAM (Radar Absorptive Material) systems, particularly to those required to resist high temperatures for significant periods of time.
Current radar absorbers are usually of the sandwich or graded dielectric type. The sandwich type absorbers utilize conductive films spaced from a ground plane; the overall impedance of the system is adjusted to match that of free space as nearly as possible. Graded dielectric absorbers consist of a series of layers having increasing dielectric and loss constants for absorbing incident radar energy with minimum reflection at the front surface and the intermediate interfaces. In either case, the absorbers have been constructed from resinous organic materials that cannot resist temperatures above 1000.degree. F for any significant period of time and from ceramic materials that are excessively heavy. A lightweight, heat resistant radar absorber is needed, especially for use in re-entry vehicles.